Facebook, the world's most popular app, accounts for a quarter of time spent using Android and iOS apps

Facebook closely trailed Google Maps for the title of the most used app on Android and Apple iOS, but the social networking giant has run away to secure the top spot, according to the most recent comScore Mobile Metrix ranking. Facebook has become the most used smartphone app among adults in the U.S., reaching 85.5 million monthly unique users. Google Maps fell to second place at 74.6 million unique visitors, and charts from comScore suggest that the decline can be attributed to Apple's decision to use its own Maps in iOS 6. Google Maps' number of monthly visitors takes a sharp dip in September, when iOS 6 debuted, and then slowly begins to rise in November.

As encouraging as the number of users may be, Facebook is also winning when it comes to time spent within one app. Winning might not be the right word because that would imply that there's competition, of which there isn't any - Facebook accounts for 23 percent of time spent within mobile apps. Nearly a quarter of the time spent in apps on Android or iOS are spent using Facebook, making it far and away the most engaging app on either platform. Following Facebook are Instagram, Gmail, and YouTube, which each account for 3 percent of time spent within apps.

According to comScore, the Top 10 mobile apps in the U.S., as measured by unique visitors, are: